As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DECLARED EMERGENCY - CABIN ALT WARNING HORN SOUNDED WHILE CLIMBING ABOVE FL 260. BOTH PACK SWITCHES IN AUTO POSITION BOTH BLED SWITCHES IN POSITION. ISO VALVE IN AUTO MODE. EMERGENCY DESCENT INITIATED. LEVELED OFF AT 10,000 FT / PASSENGER OXYGEN MASKS NEVER DROPPED. NO C/BS POPPED. REMOVED AND REPLACED VALVE AND CABIN PRESSURE CONTROLLER PER M/M. (SUBMITTED AS A SUPPLEMENT, COULD NOT FIND ORIGINAL)